Desulphurizing rayon in the package form



Patented Get. 31, 1933 stares DESULPH URIZING RAYON IN THE PACKAGE FORMHayden Benjamin Kline, Cleveland, Ohio, .assignor to Industrial RayonCorporation, Cleveland, Ohio No Drawing.

2 Claims.

One of the objects of this invention is to effectually remove sulphurfrom viscose rayon after spinning, by dissolving the sulphur on and inthe filaments by the use of those sulphides and polyi1 sulphides insolution, in which the metallic portion of the binary compound may beany metal or radical (inorganic or organic) which specifically does notappreciably react with the material on which the filaments are placed toform soluzwi ble compounds, or which will not hydrolyze to create ahydroxyl-ion concentration which in itself will cause, or tend to cause,damage or corrosion to the material on which the rayon is placed, or thematerial of which the desulphurizing apparatus is constructed.

By package is to be understood the filaments wound on bobbin or spinningspool, or any other suitable arrangement whereby liquid is drivenpositively thru the cake of filaments. The material on which thefilaments are placed is usually aluminum, rubber, phenolaldehydecondensation products, or stainless steel, and the desulphurizingapparatus is usually constructed of such materials as iron or a ferrousalloy, alumi- I num, nickel, wood and rubber.

Another of the objects of this invention is to effectually remove thesulphur from the filaments, without attacking the non-rayon componentsof the system, and hence preventing contamination of the rayon withtheir products of decomposition, and to make the process easier and moreefiicient by using an agent which does not cause excessive swelling andsubsequent shrinkage of the rayon-such as results from the employment ofsodium hydroxide.

The invention may be carried into effect by the employment of ammoniumsulphide or ammonium polysulphide, or sulphide of a metal or radical, orof a basic inorganic or organic radical which in solution, aqueous orotherwise, does not appreciably attack the spool, or which does notresult in a hydroxyl-ion concentration sufiicient to cause appreciablecorrosion of the materials normally employed upon which the package isformed, or of the apparatus in which the package is treated. Sulphide ofammonia under conditions employed in this invention may be handled iniron apparatus in the cold, and aluminum (the usual component of thespool) is not affected. In addition to being an exceptionally efficientdesulphurizing agent in this respect, ammonium sulphide is satisfactoryfrom the viewpoint of minimum corrosion.

Sodium sulphide or potassium sulphide are inapplicable in this method ofviscose rayon desul- Application March 20, 1939 Serial No. 437,626

phurization, for sodium or potassium ions in the proper environment willconvert aluminum to sodium aluminate, whereas ammonium salts herein usedwill not, within the range of environment compreheneded in thisinvention. Moreover to there are some acid desulphurizing agents such assodium acid sulphite, which evolve sulphur dioxide gas, which do notseriously attack the spools but which do attack iron or ferrous alloysof which the desulphurlzing bath is usually con-' structed, and arethereby contra-indicated and disclaimedin this invention.

As an illustration of carrying my invention into effect for thedesulphurization of viscose rayon filaments wound on aluminum spools inapparatus using iron pipe lines, etc., I may employ as the sulphurremoving solution an aqueous solution containing 0.6% of ammoniumsulphide, to which sufiicient ammonium hydroxide is added so that when aportion of the bath is tested by the addition thereto of a small amountof saturated aqueous solution of magnesium sulphate,

a light precipitate of magnesium hydroxide will be formed (solubilityproduct 1.2 1014), indicating a hydrogen ion concentration at which socorrosion of both aluminum and iron is minimized. (See Hydrogen Ions, byBritton, 1929 ed., p. 258.) The rayon is immersed, circulated orotherwise brought into contact with the desulphurizing solution untilall sulphur has been removed, after which the package containing therayon is washed free from reactants and is otherwise treated byways nowknown.

It is to be understood that the above example is given merely forpurposes of illustration, and may be departed from materially withoutaffecting the essence and underlying principles of this invention. Wherea partial vacuum is used to serve as the motive force for driving thedesulphurizing solution thru the more or less compact cake of rayon, thevacuum efficiency is regulated by the vapor pressure of the solution,which in turn depends upon the temperature. For this reason bestefliciency is obtained when a solution is used in the cold. The mixturespecified 190 is of this type. No question of the color is involved, asin the process ,of U. S. P. 1,702,837 of Merriman.

Instead of ammonium sulphide, many other sulphur-containing compoundsare suitable in that they fulfill the conditions as above outlined.Satisfactory results have been obtained by me in the employment of alkylsubstituted ammonium sulphides, such as dimethyl ammonium sulphide ordiethyl ammonium sulphide or aryl ammonium sulphides. Where the sulphideis of limited solubility in water, the material is dissolved in anappropriate solvent or solvent combination before use, or may beemployed in a finely divided condition in suspension, or only partiallyin solution. a

I hereby claim:-

1. A method of desulphurizing rayon in package form with minimum efiectupon or contamination by the material of either the device on which therayon is held or the apparatus in which it is desulphurized, where saidmaterial includes one substance affected less as the solution is mademore alkaline and another substance ati'ected less as the solution ismade more acid, consisting in treating the rayon in such package form insuch apparatus in a solution or sulphide or ammonia containing ammoniumhydrate in such quantity that the hydroxyl ion concentration or thesolution is such that eflect upon and contamination by both or saidsubstances is minimized.

2. A method of desulphurizing rayon in package form with minimum effectupon or contamination by the material of either the device on which therayon is held or the apparatus in which it is desulphurized, where saidmaterial includes both iron and aluminum, consisting in treating therayon in such package form in such apparatus in a solution of sulphideof ammonia containing ammonium hydrate in such quantity that thehydroxyl ion concentration 01 the solution is such that eiIect upon andcontamination by both iron and aluminum isminimized.

HAYDEN B. KLINE.

